Remove quotes in `LDAP_SEARCH_FILTER` example (#12019)

.env.production.sample

@@ -178,7 +178,7 @@ STREAMING_CLUSTER_NUM=1
 # LDAP_BIND_DN=
 # LDAP_PASSWORD=
 # LDAP_UID=cn
-# LDAP_SEARCH_FILTER="%{uid}=%{email}"
+# LDAP_SEARCH_FILTER=%{uid}=%{email}
 
 # PAM authentication (optional)
 # PAM authentication uses for the email generation the "email" pam variable